Symmetrical power stages for high power integrated circuits

ABSTRACT

A circuit assembly for a power converter includes a substrate, power stage integrated circuit (IC) dies, and output inductors that connect switch nodes of the power stage IC dies to an output node of the power converter. The power stage IC dies are mounted on one side of the substrate and the output inductors are mounted on an opposing side of the substrate. Two output inductors go through a magnetic core. A heatsink is attached to surfaces of the power stage IC dies. A power stage IC die has a pair of switching transistors, and a switch node formed by the switching transistors is connected by an output inductor to the output node of the power converter.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No. 16/438,063, filed on Jun. 11, 2019, which is a continuation of U.S. patent application Ser. No. 15/784,430, filed on Oct. 16, 2017, now U.S. Pat. No. 10,361,631, which claims the benefit of U.S. Provisional Application No. 62/572,333, filed on Oct. 13, 2017 and the benefit of U.S. Provisional Application No. 62/568,391, filed on Oct. 5, 2017. The aforementioned related applications are incorporated herein by reference in their entirety.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present invention relates generally to electrical circuits, and more particularly but not exclusively to circuit assemblies with high power integrated circuits.

2. Description of the Background Art

Power converters are employed to provide a supply voltage to various electrical devices. The output power of a power converter may be increased by adding output phases. Although not usually a problem with discrete circuits, a multiphase power converter in integrated circuit (IC) form may generate excessive heat that may be difficult to dissipate without making compromises to the form factor of the substrate containing the power converter.

SUMMARY

In one embodiment, a circuit assembly for a power converter includes a substrate, power stage integrated circuit (IC) dies, and output inductors that connect switch nodes of the power stage IC dies to an output node of the power converter. The power stage IC dies are mounted on one side of the substrate and the output inductors are mounted on an opposing side of the substrate. Two output inductors go through a magnetic core. A heatsink is attached to surfaces of the power stage IC dies. A power stage IC die has a pair of switching transistors, and a switch node formed by the switching transistors is connected by an output inductor to the output node of the power converter.

These and other features of the present invention will be readily apparent to persons of ordinary skill in the art upon reading the entirety of this disclosure, which includes the accompanying drawings and claims.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of a power converter in accordance with an embodiment of the present invention.

FIG. 2 is a plan view of a circuit assembly of the power converter of FIG. 1 in accordance with an embodiment of the present invention.

FIG. 3 is a plan view of the circuit assembly of FIG. 2, showing pads of a power stage block, in accordance with an embodiment of the present invention.

FIG. 4 is a plan view of the circuit assembly of FIG. 2, showing output inductors of a power stage block, in accordance with an embodiment of the present invention.

FIGS. 5 and 6 are side views of the circuit assembly of FIG. 4 in accordance with an embodiment of the present invention.

FIGS. 7 and 8 are side views of the circuit assembly of FIG. 4 in accordance with another embodiment of the present invention.

FIGS. 9 and 10 are side views of the circuit assembly of FIG. 4 in accordance with another embodiment of the present invention.

The use of the same reference label in different drawings indicates the same or like components.

DETAILED DESCRIPTION

FIG. 1 is a schematic diagram of a power converter 100 in accordance with an embodiment of the present invention. In the example of FIG. 1, the power converter 100 is a multiphase power converter. The power converter 100 includes a plurality of power stage integrated circuit (IC) dies 110 (110-1, 110-2), one for each output phase. A controller 105 (e.g., PWM controller) generates drive signals DRIVE-1, DRIVE-2, . . . , DRIVE-n, one for each power stage IC die 110, to convert an input voltage VIN to an output voltage VOUT. An input capacitor CIN receives the input voltage VIN at a node 130. The output voltage is developed across an output capacitor COUT at a node 131.

In the example of FIG. 1, the controller 105 is external to the power stage IC dies 110. In other embodiments, a power stage IC die 110 may internally include an integrated controller.

In the example of FIG. 1, a power stage IC die 110 includes a driver circuit 112, a high side switch Q1 (e.g., MOS transistor), and a low side switch Q2 (e.g., MOS transistor). The power stage IC die 110 may include a node 101 for electrically connecting an electrode (e.g., drain) of the high side switch Q1 to the node 130 to receive the input voltage VIN, a node 102 for electrically connecting a switch node SW to a corresponding output inductor 120 (120-1, 120-2), and a node 103 for electrically connecting an electrode (e.g., source) of the low side switch Q2 to a ground reference.

In one embodiment, the output inductors 120-1 and 120-2 are magnetically coupled by a magnetic core 122 in a so-called inductor-coupled topology. In other embodiments, the magnetic core 122 is omitted, and the output inductors 120-1 and 120-2 are conventional output inductors. A first end of an output inductor 120 is electrically connected to a corresponding switch node 102 and a second end of the output inductor 120 is electrically connected to the common output node 131 to provide the output voltage VOUT on the output capacitor COUT.

FIG. 2 is a plan view of a circuit assembly 202 of the power converter 100 in accordance with an embodiment of the present invention. In the example of FIG. 2, the circuit assembly 202 has a layout that includes a plurality of power stage blocks 250 (250-1, 250-2, 250-3, 250-4) that are formed on a substrate 200. Each power stage block 250 includes two power stage IC dies 110 to provide two output phases per block. Each power stage block 250 may occupy an X by Y area of the substrate 200. In one embodiment, each power stage block 250 is formed on a 10 mm×10 mm area of the substrate 200 and provides two output phases. The circuit assembly 202 may be configured to have a power rating of 500 W, for example.

In the example of FIG. 2, the boundaries of the power stage blocks 250 all meet at a center 256. The power stage blocks 250 are symmetrically arranged for optimum power delivery. The following description of the power stage block 250-1 applies to the other power stage blocks 250.

In the example of FIG. 2, the power stage block 250-1 comprises a plurality of power stage IC dies 110, a plurality of capacitors 254, and a plurality of capacitors 255. The capacitors 255 are electrically connected in parallel to form the input capacitor CIN, and the capacitors 254 are electrically connected in parallel to form the output capacitor COUT. A power stage IC die 110-1 and a power stage IC die 110-2 are mounted on the substrate 200, with the capacitors 255 being mounted on the substrate 200 between the power stage IC dies 110-1 and 110-2. The capacitors 254 are mounted on the substrate 200 in an output capacitor region 253-1.

As shown in FIG. 2, the boundaries of the output capacitor regions 253 (253-1, 253-2, 253-3, 253-4) of the power stage blocks 250 are adjacent to one another. Because the capacitors 254 form the output capacitors COUT, the layout of the output capacitor regions 253 facilitates inter-connection of the output capacitors COUT. In the example of FIG. 2, the circuit assembly 202 includes eight power stage IC dies 110 (110-1, 110-2, . . . , 110-8), thereby providing eight output phases. The output capacitors COUT of the power stage blocks 250 are coupled to the same output node 131 of the power converter 100 to provide an eight-phase output voltage VOUT.

FIG. 3 is a plan view of the circuit assembly 202 of the power converter 100, showing pads 311-314 of the power stage block 250-1, in accordance with an embodiment of the present invention. In one embodiment, the pads 311-314 are solder pads on the substrate 200. In the example of FIG. 3, the pad 311 is electrically connected to the switch node SW (see FIG. 1, 102) of the power stage IC die 110-1, and the pad 314 is electrically connected to the switch node SW of the power stage IC die 110-2. The pads 312 and 313 are electrically connected to the common output voltage node (see FIG. 1, 131). The first end of the output inductor 120-1 may be electrically connected to the pad 311 and the second end of the output inductor 120-1 may be electrically connected to the pad 313. Similarly, the first end of the output inductor 120-2 may be electrically connected to the pad 312 and the second end of the output inductor 120-2 may be electrically connected to the pad 314.

FIG. 4 is a plan view of the circuit assembly 202 of the power converter 100, showing the output inductors 120 of the power stage block 250-1, in accordance with an embodiment of the present invention. In one embodiment, as later described with reference to FIGS. 5 and 6, the output inductors 120 are mounted on the same side of the substrate 200 as the power stage IC dies 110. In other embodiments, as later described with reference to FIGS. 7 and 8, the power stage IC dies 110 are embedded in the substrate 200. In other embodiments, as later described with reference to FIGS. 9 and 10, the output inductors 120 are mounted on the side of the substrate 200 that is opposite to the side of the substrate 200 where the power stage IC dies 110 are mounted. In general, in light of the present disclosure, the components of the circuit assembly 202 may be in different locations depending on the particular application. Components of the circuit assembly 202 may be electrically connected by way of vias, electrical traces on a surface of the substrate 200, interconnect lines embedded in the substrate 200, etc., without detracting from the merits of the present invention.

In the example of FIG. 4, the first end of the output inductor 120-1 is electrically connected to the pad 311, and the second end of the output inductor 120-1 is electrically connected to the pad 313. Similarly, the first end of the output inductor 120-2 is electrically connected to the pad 312, and the second end of the output inductor 120-2 is electrically connected to the pad 314. An output inductor 120 may be electrically connected to a pad by soldering, for example. The magnetic core 122 is indicated in FIG. 4 as dashed lines.

In the example of FIG. 4, an arrow 402 points to one side of the power stage block 250-1, and an arrow 403 points to another side of the power stage block 250-1. For clarity of illustration, the intervening power stage block 250-3 (see FIG. 2) is not shown in subsequent figures showing the side pointed by the arrow 403.

FIGS. 5 and 6 are side views of the circuit assembly 202 of the power converter 100 in accordance with an embodiment of the present invention. FIG. 5 shows the side of the circuit assembly 202 viewed in a direction pointed by the arrow 402, and FIG. 6 shows the side of the circuit assembly 202 viewed in a direction pointed by the arrow 403 (see FIG. 4). In the example of FIGS. 5 and 6, the substrate 200 is relabeled as “200A” to indicate that it is a heat-dissipating substrate, such as a Bismaleimide-Triazine resin substrate. Use of a heat-dissipating substrate advantageously allows heat dissipation without necessarily using a heatsink. The substrate 200A may have embedded copper layers for additional heat dissipation.

In the example of FIG. 5, the substrate 200A has a side 503 and an opposing side 504. The power stage IC dies 110 are mounted on the side 503. The inductors 120 go through the magnetic core 122 and are formed over the power stage IC dies 110 on the side 503. A system on chip (SOC) die 502 is mounted on the side 504. The die 502 may comprise an integrated circuit that is powered by the output of the power converter 100. FIG. 6 shows the side view of the substrate 200A, viewed from the direction pointed by the arrow 403.

FIGS. 7 and 8 are side views of the circuit assembly 202 of the power converter 100 in accordance with an embodiment of the present invention. FIG. 7 shows the side of the circuit assembly 202 viewed in a direction pointed by the arrow 402, and FIG. 8 shows the side of the circuit assembly 202 viewed in a direction pointed by the arrow 403 (see FIG. 4). The example of FIGS. 7 and 8 are the same as in FIGS. 5 and 6 except that the power stage IC dies 110 are embedded in the substrate 200A.

FIGS. 9 and 10 are side views of the circuit assembly 202 of the power converter 100 in accordance with an embodiment of the present invention. FIG. 9 shows the side of the circuit assembly 202 viewed in a direction pointed by the arrow 402, and FIG. 10 shows the side of the circuit assembly 202 viewed in a direction pointed by the arrow 403 (see FIG. 4). In the example of FIGS. 9 and 10, the substrate 200 is relabeled as “200B” to indicate that it is a printed circuit board (PCB).

In the example of FIG. 9, the substrate 200B has a side 703 and an opposing side 704. The power stage IC dies 110 are mounted on the side 703. An optional heatsink 701 may be attached to the power stage IC dies 110 for heat dissipation. The inductors 120 go through the magnetic core 122 and are mounted on the side 704. An SOC die or other integrated circuit (not shown) that receives power from the power converter 100 may be mounted on either side of the substrate 200B. FIG. 10 shows the side view of the substrate 200B, viewed from the direction pointed by the arrow 403.

While specific embodiments of the present invention have been provided, it is to be understood that these embodiments are for illustration purposes and not limiting. Many additional embodiments will be apparent to persons of ordinary skill in the art reading this disclosure. 

What is claimed is:
 1. A circuit assembly comprising: a substrate having a first side and a second side that is opposite the first side; a first power stage integrated circuit (IC) die that is mounted on the first side of the substrate; a second power stage IC die that is mounted on the first side of the substrate; a first output inductor that is mounted on the second side of the substrate, the first output inductor having a first end that is coupled to a switch node of the first power stage IC die and a second end that is coupled to an output node of a power converter; a second output inductor that is mounted on the second side of the substrate, the second output inductor having a first end that is coupled to a switch node of the second power stage IC die and a second end that is coupled to the output node of the power converter; and a magnetic core, the first output inductor and the second output inductor being disposed through the magnetic core.
 2. The circuit assembly of claim 1, further comprising: a heatsink that is attached to a surface of the first power stage IC die and to a surface of the second power stage IC die.
 3. The circuit assembly of claim 1, further comprising: an integrated circuit that is powered by a voltage at the output node of the power converter.
 4. The circuit assembly of claim 3, wherein the integrated circuit that is powered by the voltage at the output node of the power converter is mounted on the first side of the substrate.
 5. The circuit assembly of claim 3, wherein the integrated circuit that is powered by the voltage at the output node of the power converter is mounted on the second side of the substrate.
 6. The circuit assembly of claim 3, wherein the integrated circuit that is powered by the voltage at the output note of the power converter is a system on a chip (SOC).
 7. The circuit assembly of claim 1, wherein the first power stage IC die comprises: a first switch having a first end that is coupled to an input voltage node of the power converter and a second end that is coupled to the switch node of the first power stage IC die; and a second switch having a first end that is coupled to the switch node of the first power stage IC die and a second end that is coupled to a reference node.
 8. The circuit assembly of claim 7, wherein the second power stage IC die comprises: a third switch having a first end that is coupled to the input voltage node of the power converter and a second end that is coupled to the switch node of the second power stage IC die; and a fourth switch having a first end that is coupled to the switch node of the second power stage IC die and a second end that is coupled to the reference node.
 9. A circuit assembly comprising: a substrate having a first side and a second side that is opposite the first side; a first power stage integrated circuit (IC) die that is mounted on the first side of the substrate, the first power stage IC die comprising a first switch and a second switch, the first switch having a first end that is coupled to an input voltage node of a power converter, wherein a second end of the first switch and a first end of the second switch are coupled to a switch node of the first power stage IC die; a second power stage IC die that is mounted on the first side of the substrate, the second power stage IC die comprising a third switch and a fourth switch, the third switch having a first end that is coupled to the input voltage node of the power converter, wherein a second end of the third switch and a first end of the fourth switch are coupled to a switch node of the second power stage IC die; a first output inductor that is mounted on the second side of the substrate, the first output inductor having a first end that is coupled to the switch node of the first power stage IC die and a second end that is coupled to an output node of the power converter; a second output inductor that is mounted on the second side of the substrate, the second output inductor having a first end that is coupled to the switch node of the second power stage IC die and a second end that is coupled to the output node of the power converter; and a magnetic core, wherein the first output inductor and the second output inductor are formed through the magnetic core.
 10. The circuit assembly of claim 9, further comprising: an integrated circuit that is powered by the power converter.
 11. The circuit assembly of claim 10, wherein the integrated circuit that is powered by the power converter comprises a system on a chip (SOC).
 12. The circuit assembly of claim 10, wherein the integrated circuit that is powered by the power converter is mounted on the first side of the substrate.
 13. The circuit assembly of claim 10, wherein the integrated circuit that is powered by the power converter is mounted on the second side of the substrate.
 14. The circuit assembly of claim 9, further comprising: a heatsink that is attached to a surface of the first power stage IC die and to a surface of the second power stage IC die.
 15. A circuit assembly comprising: a substrate having a first side and a second side that is opposite the first side; a first power stage integrated circuit (IC) die that is mounted on the first side of the substrate, the first power stage IC die having an input node that is coupled to an input voltage node of a power converter; a second power stage IC die that is mounted on the first side of the substrate, the second power stage IC die having an input node that is coupled to the input voltage node of the power converter; a first output inductor that is mounted on the second side of the substrate, the first output inductor having a first end that is coupled to a switch node of the first power stage IC die and a second end that is coupled to an output voltage node of the power converter; a second output inductor that is mounted on the second side of the substrate, the second output inductor having a first end that is coupled to a switch node of the second power stage IC die and a second end that is coupled to the output voltage node of the power converter; and a heatsink that is attached to a surface of the first power stage IC die and to a surface of the second power stage IC die.
 16. The circuit assembly of claim 15, further comprising: a magnetic core, wherein the first output inductor and the second output inductor are within the magnetic core.
 17. The circuit assembly of claim 16, further comprising: an integrated circuit that is powered by a voltage at the output voltage node of the power converter.
 18. The circuit assembly of claim 17, wherein the integrated circuit that is powered by the voltage at the output voltage node of the power converter comprises a system on a chip (SOC).
 19. The circuit assembly of claim 15, wherein the first power stage IC die comprises: a first switch having a first end that is coupled to the input node of the first power stage IC die and a second end that is coupled to the switch node of the first power stage IC die; and a second switch having a first end that is coupled to the switch node of the first power stage IC die and a second end that is coupled to a reference node of the power converter.
 20. The circuit assembly of claim 19, wherein the second power stage IC die comprises: a third switch having a first end that is coupled to the input node of the second power stage IC die and a second end that is coupled to the switch node of the second power stage IC die; and a fourth switch having a first end that is coupled to the switch node of the second power stage IC die and a second end that is coupled to the reference node of the power converter. 